Quenching

The cooling of a heated metal through its transformation range, usually by immersing it in a liquid such as oil, water, molten salt or lead. Quenching is an integral part of most processes for the hardening of steel. Except for gas, it is essential that the cooling medium be controlled at a specified temperature and the material be immersed until it has attained the quench temperature throughout its mass. See Patenting and Patenting, Lead. When applicable, the following more specific terms are used: direct quenching, fog quenching, hot quenching, interrupted quenching, selective quenching, spray quenching and time quenching.